drm/tve200: Pass NULL format_modifier to drm_simple_display_pipe_init

This Fixes build on branches where we already have format-modifier.

Reference: https://lists.freedesktop.org/archives/dri-devel/2017-August/151044.html
Fixes: 179c02fe90a4 ("drm/tve200: Add new driver for TVE200")
Cc: Linus Walleij <[e-mail]>
Cc: Janet Morgan <[e-mail]>
Cc: Ben Widawsky <[e-mail]>
Cc: Daniel Stone <[e-mail]> (v2)
Cc: Liviu Dudau <[e-mail]>
Cc: Daniel Stone <[e-mail]>
Signed-off-by: Rodrigo Vivi <[e-mail]>
Reviewed-by: Daniel Stone <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/tve200/tve200_display.c

···
 	ret = drm_simple_display_pipe_init(drm, &priv->pipe,
 					   &tve200_display_funcs,
 					   formats, ARRAY_SIZE(formats),
+					   NULL,
 					   &priv->connector.connector);
 	if (ret)
 		return ret;